# CVE-2026-98136: ntfs: bound $AttrDef table walk to the loaded table size

> A missing bounds check in the Linux kernel NTFS driver allows out-of-bounds reads when processing malformed $AttrDef tables, potentially causing crashes or data leaks.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-98136, GHSA-v5r3-r9hr-q598, UBUNTU-CVE-2026-98136

## What is CVE-2026-98136?

CVE-2026-98136 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

ntfs: bound $AttrDef table walk to the loaded table size

ntfs_attr_find_in_attrdef() walks the in-memory $AttrDef table, but the
loop condition bounds only the start of each entry, not the whole entry:

	for (ad = vol->attrdef; (u8 *)ad - (u8 *)vol->attrdef <
			vol->attrdef_size && ad->type; ++ad)

struct attr_def is 160 bytes; the guard reads ad->type at offset 128 and
the loop body reads further fields. vol->attrdef is kvzalloc(i_size),
where i_size is the on-disk $AttrDef data size, checked in
load_and_init_attrdef() only as 0 < i_size <= 0x7fffffff. A volume whose
$AttrDef data size is smaller than one entry (e.g. 120 bytes) makes the
read of ad->type run past the allocation. Creating a file reaches this
through ntfs_attr_size_bounds_check() and reads out of bounds:

  BUG: KASAN: slab-out-of-bounds in ntfs_attr_find_in_attrdef+0x66/0xa0
  Read of size 4 at addr ffff888005833280 by task init/1
   ntfs_attr_find_in_attrdef
   ntfs_attr_size_bounds_check
   ntfs_attr_can_be_non_resident
   ntfs_attr_add

Require the whole entry to lie within attrdef_size in the loop guard, and
reject at mount a $AttrDef too small to hold one attr_def entry.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-98136?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-98136?

Apply the vendor's patch.

## Is CVE-2026-98136 being exploited?

There is no known exploitation of CVE-2026-98136 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98136 and fix it if it is affected.

What it is: CVE-2026-98136 is a high-severity memory corruption vulnerability in Linux kernel, published on 25 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98136 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98136/ (Markdown: https://insights.sbomify.com/CVE-2026-98136/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98136
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98136
- OSV: https://osv.dev/vulnerability/CVE-2026-98136

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98136/
Summaries are generated and may contain mistakes; the official description above is the record.